The preferred embodiment concerns a device for sealing a shaft against the penetration of a toner mixture, in which an annular, stationary sealing device is arranged at a distance of an annular gap around a shaft, and the annular gap is charged with a magnetic field. The preferred embodiment also concerns a method for sealing a shaft against the penetration of a toner mixture.
Rollers (for example magnetic rollers, developer rollers and transport rollers) that respectively comprise a shaft are used in developer stations for electrographic printers or copiers. In a developer station, these shafts can come into contact with a toner mixture comprising magnetic carrier particles and toner particles. The respective shaft is borne in bearings, for example in a slide bearing, ball bearing, radial bearing or roller bearing. If magnetic carrier particles or toner particles enter into this bearing, the bearing can be damaged, with the result that its predetermined service life is not reached and it has to be exchanged early.
A magnetic seal for shafts in a developer station of a printer is known from DE 696 27 225 T2 (corresponding to EP 0 723 211 B1). A magnetic ring that holds the magnetic carrier particles within a magnetic field is used to seal the magnet ring, such that the carrier particles cannot pass through an annular gap between the magnetic ring and a shaft. Different profiled sheets that bundle the magnetic flux so that the sealing effect against the passage of magnetic carrier particles is improved are described in the document.
JP 05 127464 A describes a magnetic bearing to bear a photoconductor roller in an image generating apparatus. The magnetic bearing contains a magnetic fluid which seals the bearing air-tight against the penetration of toner or paper dust.
US-B1-6 377 770 describes a slide bearing for use in a developer station. The slide bearing uses various substances that provide sliding properties and sealing properties.